Repairing Ignorance
by rumblestiltsken
Summary: Fork of Harry Potter and the Methods of Rationality, exploring the intersection between rationality and human psychology. Knowing and doing are two different things, no matter how smart you might be. Divergence at chapter 91. If you haven't read HPMOR, and you should, beware the SPOILERS.
1. Chapter 1

REPAIRING IGNORANCE

* * *

The door swung shut behind him with a gentle click.

He had said he would only need two minutes. He hadn't lied.

It would either work or it wouldn't. Everything he had experienced so far seemed to suggest it would, and the hope burned in him like a raging inferno.

If it didn't work ...

The time-turner could accomplish nothing. He had no resources, no leads, no way to choose between a thousand threads of potential research. No one with the knowledge required to guide him could be trusted, not with this. None had the right motivation; the _appropriate_ motivation for this time and this place. They would keep him occupied and distracted.

And those that would help, those who were coming to understand the world as it was, they didn't have the knowledge.

It burned deep within him, that understanding. With a few well-chosen questions to someone with enough power and he could have narrowed his search immensely, perhaps constrained it enough to fit within the time-turner's limit. But there was no-one to ask. Even the defense professor had been evasive, tempting him to waste his time. Any answers he provided would be suspect.

So all he had left was his own hubris.

He could practically hear _her_ voice, words of warning he had never heeded. Unintended consequences. The risk of vaporised death that lurked hidden inside transfiguration experiments, the improved Patronus that swallowed life as fuel.

Not for the first time he cursed Merlin and his Interdict. The recursive irony of it; to hide the knowledge of dangerous spells one also obscured the risks associated with their rediscovery. Any witch or wizard could not know if a simple tweak to a minor spell, something a first year could do by accident or design, might unravel the foundations of reality. Magic didn't work on proportionate reactions, and taking away the knowledge took away the ability to avoid calamity.

If he had known that to destroy a single dementor would simply tire him out, but to defeat a group would take more than he could give, he would not hesitate. He would draw up a roster and work in shifts, until every scar in the world was closed.

But not knowing almost killed him, when the light filled him and his life poured out.

He shook his head. It was one thing to know about the over-confidence bias, to have trained to account for emotions like _hope_ when making his decisions, it was completely another thing to have no remaining options. To be lost and drowning and to know that you had one last chance to breathe clean air.

He had read Kahneman and Tversky of course, the fathers of modern rationality. But beyond their work with heuristics and biases, he had also learned about framing. The earliest experiments showed that the _way_ a question was asked would change the answer. The external environment influenced the decision as surely as any emotion could. He got that, on a cognitive level.

Until now he never understood the implications beyond the elegant research papers. Questions are not only asked by people, but by situations, and faced with an _unknowable _risk, or a knowable and devastating loss, he had to make a decision.

Harry Potter smiled sadly as he looked upon the body of Hermione Granger.

For whatever happened next, he blamed Merlin.

He lifted his arm, his holly and pheonix feather wand trailing streamers of golden light as it angled towards the still form that had been his friend. He uttered a single word.

* * *

"_REPARO_."

* * *

**_Muscles, bones, joints._**

_Springs, levers, pulleys._

**_Vessels, airways, gut._**

_Pipes with flexible or muscular walls._

**_Heart._**

_Pump._

**_Liver, spleen, kidneys._**

_Filters._

**_Nerves. Neurons._**

_Wires. Logic gates._

**_Cells._**

_Microscopic machines._

It wasn't enough, he knew. He pushed further.

**_Life._**

_Self-replicating and self-organising automata. Complexity from simplicity._

**_Id. Individuality._**

_Noise. Muddy signals. Probabilistic fluctuations._

**_Ego, self._**

_Recursion. Self-referential fitness mechanisms._

**_Super-ego. Rationality._**

He paused, slowed by the cognitive dissonance of the thought, but pushed onwards.

_Weighted reflexes. Aggregate external phenomena. Even more deterministic than the rest._

The wand grew brighter, ribbons of light coiled around the length, twisting impossibly through invisible dimensions.

There was still something missing. His eyes searched her motionless face, scoured her features, but could not find the key. The power in his wandtip pulsed and threatened to escape. Confusion was detected, and a well-trained pathway turned the anaysis inward.

A specific group of neurons fired and caused his lips to twitch upwards.

What do you think you know, and why do you think you know it?

**_The Hermione he imagined._**

_Mental model of reality. Flawed. The map is not the territory._

This wasn't transfiguration, partial or otherwise. He wasn't changing a thing that was into something he imagined. He was simply returning something broken to an earlier state. He looked at her and saw her. A pattern, no more and no less than any other.

The light expanded, spreading across the floor like liquid.

* * *

The disciplinarian blinked as a glittering corona of light flowed out from behind the closed door. The walls and floor turned to shimmering gold, under her feet and behind her back.

She closed her eyes and prayed her trust had been well placed.

* * *

An old man stood in a hidden room before hundreds of broken wands, lost in thoughts long trodden.

Downstairs a phoenix cocked its head in interest as several instruments that spun and twirled began to glow.

* * *

Moments before the light reached him, a being of many masks realised its mistake, and Merlin's.

He blurred into motion, all pretenses falling. Cursed fire consumed millenia old stones and diminished his body alike.

* * *

The world _skipped_ and Harry was a foot to the left, silhouetted against a stone ceiling where only an eyeblink before there had been the open cloudless sky. Her eyes struggled to adjust to the low flickering light of the magical torches.

Her mind still worked, and it told her the pain was gone.

She flexed her toes, and heard the sheet that had been draped over her rustle in response.

She narrowed her eyes.

"What did you _do_, Harry?"

A wry smile crossed his face, although it stopped short of his glistening eyes.

"The only thing I could, Hermione."

* * *

**AN: **

I have edited the story a little to make the spell and some of Harry's thought process more explicit. The spell was never meant to be ambiguous, this is Reparo 2.0, where the fixus inanimatus objectus spell can extend to all things if the caster understands reality deeply enough.

The challenge for readers here, as per the HPMOR style, is to consider the implications. What happens next? Has Harry created a safe form of resurrection, unlocked the path to godhood or fulfilled the Divination teacher's prophecy, and if so, how? What will Quirrel do when he reaches the room and finds Hermione alive? If he intends harm, can Harry stop him?

The story is complete for now, although there are several alternate endings in my head. If anyone guesses them correctly I will write each one up.


	2. Chapter 2

**Addendum to Repairing Ignorance: **

Regarding the science in this story, I recommend watching the TED talk by Dan Ariely "Are we in control of our own decisions?" I would link but not sure if that is frowned upon here. I couldn't explain it fully in the text because most of behavioural economics, and Dan Ariely in particular, do not exist in the HP timeline yet! Of course Dan Kahneman and Amos Tversky had already laid the groundwork with the referenced concept of framing, which formed part of the Prospect Theory. To explain a little further though:

The environment a person is in defines their decision space and can even make up their minds for them. The classic example is that in countries with similar culture, an opt in system of organ donation results in massively fewer organs donated than an opt out system. The paper to read is called "Do defaults save lives?", which can be found with a simple Google search.

The surprising thing is in each case the citizens feel rationally justified in their decisions, and can even explain _why_ they came to them, when in reality the person who made the form at the DMV made their decision for them. If they lived next door in the next country, they would make a different choice.

The implications are far reaching. How do you view crime if a person can be put in a situation where the majority of people would feel justified in breaking the law? How about someone being successful, if they were in a situation that made the choices to achieve success easy?

Think about how the Stanford prison experiment fits in. Normal people end up brutalizing their classmates because of the situation alone. Think about the Nazis, which in many ways is the origin of modern psychology, as scientists tried to understand how normal people could commit such terrible acts.

This understanding of the role of the environment redirects blame and credit away from individuals and onto systems. The environment is something a society can control, so a society should be held responsible for the ups and downs, rather than looking at each individual action in a vacuum. Each individual still makes a choice to differing extents, but given the right situation anyone will change their position. Like Harry here, risking it all because he had no other option. The Defense Professor would hold him responsible, but should he? Is the society that enforces ignorance not at least partially to blame?

To quote Dan Ariely from the last line of the TED talk I mentioned -

"Are we Superman? Or are we Homer Simpson?

When it comes to building the physical world, we kind of understand our limitations. We build steps. And we build [computers] that not everybody can use obviously. (Laughter) We understand our limitations,and we build around it. But for some reason when it comes to the mental world, when we design things like healthcare and retirement and stockmarkets, we somehow forget the idea that we are limited. I think that if we understood our cognitive limitations in the same way that we understand our physical limitations, even though they don't stare us in the face in the same way, we could design a better world. And that, I think, is the hope of this thing (behavioural economics)."

Thanks for reading.


End file.
